Pneumatic rubber tires are conventionally prepared with a rubber tread and supporting carcass. The carcass is conventionally composed of one or more rubberized cord reinforced plies. Such construction is well known to those having skill in such art.
Here, it is desired to provide such rubber composition which contains a relatively small amount of carbon black reinforcement on the order of about 15 to about 35 phr and in the absence, or at least substantial absence, of silica and accompanying silica coupling agent.
It is recognized that in U.S. Pat. No. 5,396,940 a carcass ply rubber composition has been disclosed which is composed of 5-95 phr of epoxidized natural rubber, 5-85 phr of silica, a silica coupler, carbon black which can be a carbon black such as N299, which can also contain 95-5 phr of other rubbers including natural rubber and cis 1,4-polybutadiene rubber.
In the description of this invention, the term "phr" where used means "parts of material by weight per 100 parts by weight of rubber".